Dear Tiziano

the environmental stress and its effect on radiocarbon dating is well explained in link below:

http://www.chcpublications.net/radcarbn.htm

Regards

Massih

Please also browse the Radiocarbon at: http://journals.cambridge.org/action/displayJournal?jid=RDC

Dear Peter

Thanks a lot, this is extremely useful|!What parameters shall i change if i want to check marine or mixed marine/estuarine organism (i.e. mangrove shells)?

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Dear Peter

Thanks again. However, the problem is that we have to deal with sites which have not yielded terrestrial organic materials to confront. The 13C variations observed show a range from -7 to +1 . We are rather sure that Siranda Lake was drying up at the time and therefore this could be an indicator of environmental stress conditions. But we have to be sure that this same conditions didn't affect the 14C content - and the consequent date. Any suggestion?

All the best!

Tiziano

This question is similar to my question. For example, the C3 and C4 plant growing in the same condition should have the same 14C age. But after correcting for the mass-dependent fractionation effect, their conventional 14C ages differ each other. My suggestion is to consider an ad hoc correction for the C4 plant , e.g. with respect to -6 per mill (the delta-13C of pre-1950 atmosphere), instead of -25 per mil.